The Incidence of Adenomatous Colon Polyps in Average Risk Patients Referred for Colorectal Cancer Screening

Abstract

Purpose: The aim of our study was to evaluate the incidence of adenomatous colon polyps in patients referred for colorectal cancer screening. Our secondary aim was to evaluate the incidence of diverticulosis as well as the success rate of complete colonoscopy with usual preparation and conscious sedation. Methods: We retrospectively evaluated all the colonoscopies performed as outpatient using conscious sedation at our Virginia Ambulatory Surgical Center in consecutive fashion from August 2002 to March 2005. All the colonoscopies were performed by a single attending gastroenterologist (KA) using Fujinon video colonoscopes. Inclusion criteria included patients 50 years old and above referred for routine screening colonoscopies. Exclusion criteria included anyone with family history of colon cancer or polyps, personal history of colon cancer or polyps, diarrhea, constipation, change in bowel habits, anemia, or rectal bleeding. Results: Of 1031 colonoscopies performed by KA, 222 procedures were excluded. Of 809 procedures evaluated, 544 (67.4%) were noted to have one or more polyps, including 2 (.25%) adenocarcinomas, 274 (33.9%) patients with tubular adenomas, 14 (1.7%) with tubulovillous adenoma, and 264 (32.6%) with hyperplastic polyps. When polyps were further categorized based on the largest size, 159 of 371 dimmunitive polyps (4mm or less) were identified as adenomas. 94 of the 129 intermediate polyps (5–9mm) were adenomas, and 29 of the 45 large polyps (>1cm) were adenomas. Cecal intubation was successful in 99.8% and terminal ileum intubation in 95 percent. Diverticulosis was present in 52.8 percent of patients. Conclusions: The incidence of colonic adenomas discovered during screening of average risk individuals was 35.6%, which is significantly higher than previously reported. Of polyps found, 53% were adenomatous or villous lesions. Surprisingly 42.8% of polyps <5mm were also adenomas. In experienced hands complete endoscopic screening of the colon is almost always possible and removal of all polyps regardless of size is important.